The Nitish Kumar-led Grand Alliance has now pulled way ahead of the BJP on a dramatic Sunday morning that has seen unprecedented confusion as votes are counted for the Bihar assembly elections.

Here are the latest developments in this story:

The Grand Alliance is now leading in 128 seats. A party or alliance needs 122 seats to form government in the 243-member Bihar assembly.

The BJP, which had led in earlier rounds, is now ahead in 99 seats.

At about 10 am, two hours into counting, there was confusion over who was leading with different TV channels making discrepant forecasts.

NDTV and some other channels showed the BJP ahead. Others, including local media in Bihar, showed the Grand Alliance ahead. The Election Commission data too showed the Nitish Kumar alliance ahead.

"This sort of discrepancy is a first," said Yogendra Yadav, psephologist and former Aam Aadmi Party leader.

"We have vigorous checks and balances in place, we are rechecking all the data," said NDTV's Prannoy Roy on air.

Amid the confusion, there were celebrations in both camps. The BJP in Patna ordered a 100 kg of sweets. At the homes of Chief Minister Nitish Kumar and his ally Lalu Yadav, supporters danced.

The BJP has fought the election in alliance with three regional parties which have support among the Dalits and Other Backward Castes, who constitute about 50 per cent of Bihar's population.

With the BJP not naming a chief ministerial candidate, Nitish Kumar faced off with PM Modi and sought to project the (outsider)" in a campaign that was bitter, with attacks from both sides often personal.

A win in Bihar will boost PM Modi's chances of building the parliamentary strength he needs to push through key reforms. The government is in a minority in the Rajya Sabha, which is selected on the basis of parties' strength in state assemblies.